Important note: Information in this article was accurate in December 2002. The state of the art may have changed since the publication date.AIDSWEEKLY Plus; Monday, December 23, 2002
Michael Greer, Senior Medical Writer
"Originally identified as the gamma interferon-inducing factor, interleukin-18 (IL-18) was rediscovered as a proinflammatory cytokine related to the IL-1 family of cytokines that plays an important role in both innate and adaptive immune responses against viruses and intracellular pathogens," explained Rasheed Ahmad and colleagues at the University of Montreal.
HIV patients showed elevated serum levels of IL-18 and - somewhat paradoxically - impaired production of the cytokine from peripheral blood mononuclear cells (PBMCs), Ahmad and coauthors found.
The researchers investigated IL-18 levels in volunteers suffering from HIV infection. These patients demonstrated significantly higher levels of serum IL-18 than seronegative controls, according to the report.
Surprisingly, however, HIV patients also showed impaired PBMC production of IL-18 after lipopolysaccharide stimulation. Expression of activated caspase-1 by stimulated PBMCs was also significantly lower in patients compared with controls, study data showed.
Seropositive patients carried elevated levels of transforming growth factor beta, which can inhibit IL-18 release by peripheral blood cells (Elevated levels of circulating interleukin-18 in human immunodeficiency virus-infected individuals: Role of peripheral blood mononuclear cells and implications for AIDS pathogenesis. J Virol 2002 Dec;76(24):12448-56.
"The elevated levels of IL-18 in the serum of HIV-infected individuals may contribute to AIDS pathogenesis," Ahmad and colleagues concluded, "whereas its compromised production from their PBMC in response to stimuli may reduce their innate defense to opportunistic intracellular pathogens."
The corresponding author for this report is Ali Ahmad, Laboratory of Immunovirology, Pediatric Research Center, and Department of Microbiology and Immunology, University of Montreal and Sainte-Justine Hospital, Montreal, Quebec H3T 1C5, Canada. E-mail: ahmada@justine.umontreal.ca.
Key points reported in this study include:
Iinterleukin (IL)-18 may play a key role in HIV/AIDS pathogenesis
Serum IL-18 levels were elevated in HIV patients
However, these patients also demonstrated impaired IL-18 production by peripheral blood cells
This article was prepared by AIDS Weekly editors from staff and other reports.
Reference
Ahmad R, Sindhu ST, Toma E, et al., "Elevated levels of circulating interleukin-18 in human immunodeficiency virus-infected individuals: role of peripheral blood mononuclear cells and implications for AIDS pathogenesis", J Virol 2002 Dec;76(24):12448-56.
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